Consistant and quantitative method for tco delamination evaluation

Abstract

A method and apparatus for manufacturing photovoltaic cells is provided. In one embodiment, a method for evaluating transparent conductive oxide (TCO) delamination from a substrate is provided. The method comprises providing a glass substrate with a TCO film laminated on a first surface of the glass substrate, depositing a metal layer on a second surface of the glass substrate opposite the first surface, heating the substrate while applying a bias to the substrate, cooling the substrate in a humidity controlled environment for a fixed time period, dividing the TCO film into a plurality of electrically insulated channels using a laser scribing process, and measuring a resistance of each of the plurality of electrically insulated channels.

1 . A method of evaluating a transparent conductive oxide (TCO) delamination from a substrate, comprising:
 providing a glass substrate comprising:
 a TCO film laminated on a first surface of the glass substrate; and 
 a metal layer deposited on a second surface of the glass substrate; 
   heating the substrate while applying a bias to the substrate;   exposing the heated substrate to a humidity controlled environment for a fixed time period;   dividing the TCO film into a plurality of electrically insulated channels; and   measuring a resistance of each of the plurality of electrically insulated channels.   
   
   
       2 . The method of  claim 1 , further comprising:
 comparing the resistance of each of the plurality of electrically insulated channels with a desired delamination resistance to determine which of the plurality of electrically insulated channels have suffered delamination and which of the plurality of electrically insulated channels are still functional.   
   
   
       3 . The method of  claim 2 , further comprising:
 evaluating the TCO delamination from the substrate by comparing a number of electrically insulated channels that have suffered delamination with a number of electrically insulated channels that are functional.   
   
   
       4 . The method of  claim 1 , wherein the TCO film comprises material selected from the group comprising tin oxide (SnO), zinc oxide (ZnO), and aluminum doped zinc oxide (AZO). 
   
   
       5 . The method of  claim 1 , wherein heating the substrate comprises exposing the metal layer deposited on the second surface of the glass substrate to a heat source. 
   
   
       6 . The method of  claim 5 , wherein applying a bias to the substrate comprises applying a positive bias to the metal layer and a negative bias to the TCO film. 
   
   
       7 . The method of  claim 5 , wherein the heat source is positioned in an enclosed temperature controlled chamber. 
   
   
       8 . The method of  claim 1 , wherein the metal layer is an aluminum layer. 
   
   
       9 . The method of  claim 1 , wherein the fixed time period is selected to cool the substrate to room temperature. 
   
   
       10 . A method for evaluating transparent conductive oxide (TCO) delamination from a substrate, comprising:
 providing a glass substrate with a TCO film laminated on a first surface of the glass substrate;   depositing a metal layer on a second surface of the glass substrate opposite the first surface;   heating the substrate while applying a bias to the substrate;   cooling the substrate in a humidity controlled environment for a fixed time period;   dividing the TCO film into a plurality of electrically insulated channels using a laser scribing process;   measuring a resistance of each of the plurality of electrically insulated channels.   
   
   
       11 . The method of  claim 10 , wherein the TCO film comprises material selected from the group comprising tin oxide (SnO), zinc oxide (ZnO), and aluminum doped zinc oxide (AZO). 
   
   
       12 . The method of  claim 10 , wherein the metal layer is an aluminum layer. 
   
   
       13 . The method of  claim 12 , wherein the metal layer has a thickness between about 1,000 Å and about 5,000 Å. 
   
   
       14 . The method of  claim 10 , wherein heating the substrate comprises exposing the metal layer deposited on the second surface of the glass substrate to a heat source. 
   
   
       15 . The method of  claim 14 , wherein applying a bias to the substrate comprises applying a bias between the metal layer and the TCO film. 
   
   
       16 . The method of  claim 10 , wherein the humidity controlled environment is maintained at a relative humidity (RH) between about 60% and about 100%. 
   
   
       17 . The method of  claim 16 , wherein heating the substrate comprises heating the substrate in a temperature controlled environment to a temperature of about 250° C. 
   
   
       18 . The method of  claim 15 , wherein the bias is between about 100 volts to about 250 volts. 
   
   
       19 . The method of  claim 18 , wherein the fixed time period is selected to cool the substrate to room temperature. 
   
   
       20 . The method of  claim 10 , wherein cooling the substrate in a humidity controlled environment for a fixed time period comprises positioning the substrate in an enclosed chamber with a controlled relative humidity.